I am not sure if its a problem that your customers license file says "call number is 0". It may be due to different ways a license can be created. Thats something PTC support should be able to answer - keep in mind that this forum is no official PTC support but "just" a user driven platform enabling PTC users to exchange ideas.
The two licenses clearly are for two different PTC Host IDs (= MAC address of the network interface card). This could mean that they were requested for two different computers or for two different NICs in the same machine. The latter usually is no problem for Mathcad 15 (Prime is more sensible in this respect).
Anyway I don't think that the license files have anything to do with the problem of the gray background you experience.
I had remembered a similar problem /gray background) in a thread long time ago here in the forum and at those times the reason was that Mathcad was set to kind of an exotic printer with a ridiculously tine page size. What looked gray on first sight were the page separator lines. Thats the reason I asked about the printer selected in Mathcad but I am in no way sure that you experience the same problem.
